1. Field of the Invention
The present invention relates in general to an ink jet recording apparatus, and in particular to an ink jet recording apparatus of the type in which an ink jet nozzle is mechanically vibrated in order to produce the ink droplets without fail.
2. Description of the Prior Art
According to a fundamental arrangement of the ink jet recording apparatus, pressurized ink is ejected from a nozzle. When the ink mass is broken up into ink droplets, a quantity of the electric charge conforming to the recording information is imparted to the ink droplets through an electrostatic coupling. The charged ink droplets are then passed through an electric field of a constant intensity and deflected under the influence of the prevailing electrostatic force. In view of the fact that the ink takes a stream like form immediately after the ejection from the nozzle orifice, the charging of the ink droplets is carried out by means of a charging electrode disposed so as to enclose the ink stream, wherein the electrostatic capacity formed between the ink stream and the charging electrode is charged by the voltage of the recording information signal. In other words, the ink stream in the charged state is broken up into the ink droplets, whereby the electric charge is, so to say, confined within the individual ink droplets. In order to confine the electric charge within the ink droplets at a proper and correct quantity, it is desirable that the electrostatic capacity existing between the ink stream and the charging electrode has been completely charged and is in the stable state the ink stream is broken up into the ink droplets. If the ink droplets are produced before the completion of the charging of the electrostatic capacity, it will become difficult to maintain the ratio between the magnitude of the information signal i.e. (voltage applied to the charging electrode) and the quantity of the electric charge confined in and carried by the ink droplets at a constant value. Such difficulty should of course be overcome to accomplish the correct deflection of the ink droplets.